Although PVC construction elements such as profiles are the choice of many professional and consumers because of various reasons, many people still perceive PVC construction elements as having a “plastic” look.
On the one hand, the appearances of profiles have been addressed by coating construction elements such as profile members which can be provided with a coating e.g. by spray coating or by the application of a foil provided with a coating. Spray coating has the advantage that a relatively thick coating layer of e.g. a thermosetting resin can be applied such that this layer can comprise a polymeric powder to obtain the desired grained surface structure. However, a disadvantage of providing a coating by a spray coating method on a profile member is that those surfaces of the profile member which are not to be colored have to be masked first. Then those surfaces which are to be colored, are degreased to obtain good adhesion of the coating. Then the coating is applied by means of a spray unit in two or three successive layers, to the profile member, finally followed by for example air-drying of the coating or drying of the construction elements in a heated oven. Masking, to prevent overspray on profile surfaces, which are not intended to be painted, degreasing and spraying of the construction elements are carried out manually. The mask may be in the form of a fabric and/or film layer which is pressed and/or held against the surface of the profile on which no coating is desired. The mask may be in contact with the profile only during the vacuum coating or, in other embodiments of the invention, the mask is in contact with the profile through both the coating and curing steps and/or the mask is in contact with the profile during the entire time the profile is within any of the curing and/or coating device.
The drawback of this method is that it is very labor-intensive, time-consuming and creates high amounts of waste due to masking tape or other products used to cover non-painted surfaces. This method consequently results in low productivity and is very expensive. Owing to the wide variety of construction elements such as profile members and to their dimensions on the one hand, and to the difficulty of masking different parts of them on the other hand, automation of this method cannot be achieved in an efficient manner.
On the other hand, in coating applications requiring a high quality coating finish it is generally desirable to completely and evenly coat an object to be coated with a minimum expenditure of coating. This is desirable for several reasons. First, coatings for the above mentioned profile are often expensive. Therefore, reducing coating consumption offers the immediate benefit of reduced coating cost. Second, coating material which is not deposited upon the object to be coated can be lost to the environment and this loss generally is an environmentally undesirable form of waste. Therefore, reducing the quantity of coating lost to the environment in a coating process reduces the costs of disposing of the lost coating material and reduces emissions of coating solvents. Vacuum coating processes can be used, but such processes are limited to construction elements such as profiles having leading and trailing edges. Profiles have inside surfaces which form depressed or recessed areas of the profile between the front and rear edges of the profile. These recessed areas form leading and trailing edges which extend transverse to the direction of movement of the profile through the coating apparatus.
From the above, it is made clear that an object of the present invention is to provide a reduced “non plastic look” construction, in particular profiles such as window profiles, which do not have the drawbacks of conventional PVC construction elements and suffer from the drawbacks of the processing set out above.
The present invention is directed to solving this myriad of sometimes interrelated problems in a coating process which incorporates a number of features which, in combination, produces an extremely high quality coating and even an unexpected finish on difficult articles to be coated.
A further object of the present invention is to provide a new economically process which provides for a variety of aesthetic finishes, including a range of aesthetics and textured thereby resulting in said reduced plastic look finish.
In accordance with the present invention, it has now been found that the above-described specifications can be fulfilled by coated construction elements. The present invention provides for cost efficient and effective environment friendly process as well as desired specifications and properties of the products obtained thereof.
The object is achieved by method for providing a fully colored construction element such as a profile with a coating, the method comprising a multiple step coating process for coating a substrate construction element having side portions, whereby at least three sides portions are coated, characterized in that the process comprises the steps of A) advancing the element past a first coating station on its transport side for applying a surface layer onto one or more of the non transport side portions of the element and B) subsequently advancing said element into further coating stations for applying a surface layer to the transport side of A) or/and one or more of the remaining side portion of said element.
A second aspect of the present invention provides for a coated profile that matches standard todays coated PVC profiles in terms of finish, color fastness/long term weathering performance; gloss and long term gloss retention performance; impact performance and UV aged impact performance and surface hardness/scratch resistance;
Generally, it is known to spray paint or coat construction elements by an apparatus having a conveyor which moves parts to and through some form of spraying booth where one or more nozzles coat the construction elements with a coating composition. These apparatus or systems are limited by the amount of volatile organic compounds that the sprayed coatings emit, the amount of floor space required to cure the coatings and by limited transfer efficiency.